Winter Snowstorms in the Northeast: Impact by the Numbers

[UPDATE of Feb 15, 2010: NOAA has announced that the fierce winter storm of February 4-7, 2010, which blanketed the Mid-Atlantic states with historic amounts of snow, was ranked as a Category 3 ("Major") storm event on the NESIS scale. The computed raw score was higher than even that of its December 18-21, 2009 predecessor. Here is the snowfall map.]

Earlier this month, the National Oceanic and Atmospheric Administration (NOAA) announced that the December 18-21, 2009 winter snowstorm that crippled the Mid-Atlantic and New England States was ranked among the top five worst storms of the decade to have affected the Northeast. This determination was based upon a relatively-recent storm index, known as the Northeast Storm Impact Scale (NESIS), which provides a systematic way for us to compare the impact of winter snowstorms in the Northeast urban corridor, a region extending from southern Virginia into New England. The NESIS index is not used to predict the effect of an impending snowstorm, the way Saffir-Simpson category numbers are used for hurricanes. Instead, the Northeast Storm Impact Scale provides a retrospective look at how severe a storm was — after the fact.

The NESIS index is calculated only for storms in the Northeast Corridor that leave behind large areas of 10 or more inches of snowfall. The value of the computed index depends not only on the geographic extent of the snowfall, but also on the number of people living in the path of the storm. The aerial distribution of observed snowfall and population information are combined in an equation that calculates a raw NESIS score, which in turn is converted into one of the five NESIS categories. The largest NESIS values result from storms producing heavy snowfall over large areas that include major metropolitan centers. Thus, the Northeast Storm Impact Scale may be thought of as a population-weighted storm snowfall index, useful in estimating a particular storm’s societal impacts, especially on transportation and the economy.

According to NOAA, the December 18-21, 2009 storm, which dumped top-ten snowfall amounts on Baltimore, Washington and Philadelphia, was a Category 3 (“Major”) event, on scale ranging from Category 1 (“Notable”) to Category 5 (“Extreme”). The storm did not receive a higher ranking mainly because it only struck a glancing blow to the big population centers between New York City and Boston. Here in the Capital District, the storm remained well to our south, and no snow was received at the National Weather Service in Albany. However, for residents of the Mid-Atlantic, the storm was one of the highest impact snowfalls of the past ten years, and third most potent December storm since 1960.

By way of comparison, the only Category 5 winter storms to have struck the Northeast are the “Superstorm ‘93” of March 12-14, 1993 and the “Blizzard of ’96” during January 6-8, 1996.

Ranks of 37 high-impact snowstorms that have affected the Northeast urban corridor

3 Responses

Very interesting information. I remember the storm in March of 93 quite well. My little 1980 Dodge Colt had fun surfing through the white stuff. That was the first time I had experienced the roads being closed and in the town of Fonda, where I lived at the time, seemed mild compared to other towns around the area. Being snowed in can be sort of fun as long as you have the essentials (food, water, & heat is good, too).

It’s funny what was deemed notable storms while others were ignored. The storm of January 6-8, 1996 was the most notable for me & while NOAA had the data a bit skewed, I can assure you that those of us who were living on Long Beach Island, New Jersey can tell you that there was MUCH more than what they show for the region & should have been in the red, as there was about 34″ on the ground when the storm finally moved on out of there. I’d taken a lot of flack for that situation as I was a newlywed & had told my husband before we’d moved there that it “never snows” down there & when I’d seen that the bay froze over around Thanksgiving, I knew it was going to get ugly that winter, but could never imagine it would lead to be a “state of emergency” / historical sort of winter, yeesh! We’d moved west from there later in the year & settled close to Philly, where the winters have proven to be very mellow compared to the winters of the Northern NJ/ NYC Metro area my husband & I had known our whole lives. I noticed discrepancies with other “storm totals” as the most recent on the list being the December 19-20, 2009 storm that left 27″ of snow for us in Camden County, NJ, surpassing the 10-20″ shading NOAA have us in. Is there some sort of averaging NOAA does to come up with the grading because I have seen lots of misrepresented storm totals shown on the maps? I just can’t get over the weird pattern this winter is proving to be in with Southern New Jersey / Philadelphia & the “Del-Mar-Va” region being hit harder than the Northern New Jersey / NYC & “Tri-State” area. Do you know which other winters had proved out to be the same? Thanks for this informative & interesting list of memorable snow storms. Now could you please pass the message on to Mother Nature & Jack Frost that we’ve made up for our un-snowy winters & that there’s no need to dump a whole season’s worth of snow on us with each storm, especially when we’d just gotten dug out from one 4 days earlier. Is there any former “model year” that comes close to what we’re dealing with now? I love these sort of meteorology data blogs & yours is the closest one to the area I live in & you seem to know what you’re discussing, so I’d love to know if there’s something I can look at to compare with or learn what to expect from former years.

I am surprised that the Blizzard of early February 1978 was only a Category 3, but then I read how the NESIS system is used, and under that guideline, I can understand why it was only a 3, because it did not affect the Wash.-Balt-Philly-NYC areas that much. But it decimated Boston, Providence, and the entire SE New England area completely. All businesses in Boston that were not deemed necessary for emergency services were closed for that entire Tuesday-Friday period. Storm started about 5 PM on a Monday afternoon. It is definitely the worst snowstorm I have ever lived through, and I lived nearly my entire life from 1951-1979 in the Boston area. Boston’s alltime 24-hour period snowfall had just been set 17 days earlier (21 inches, I think) and this storm surpassed that easily with something like 26 inches. The one that hit in early January 1996 was almost as bad, but I was living in a DC suburb, so that area did not suffer the super winds and flooding there that the ’78 monster had. The remainder of that ’78 winter was so cold that the Charles River on the Boston-Cambridge border was still frozen on Saint Patrick’s Day!!

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